Carbonyl complexes of palladium stabilized on phosphinated polymer supports

✍ Scribed by Alan R. Sanger; Leslie R. Schallig; Gie Tan

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 238 KB
• Volume: 35
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(00)93383-8

✦ Synopsis

No monosubstituted carbonyl or benzonitrile complex was observed. Attempts to prepare a mononuclear complex by the reaction of the dinuclear, chlorine-bridged complex 2 with CO, or by the reaction of a solution of I with an equivalent amount of PPhs, failed. These observations showed that, for mobile complexes, reaction 2 (Y = CO or PhCN) proceeds readily to the left. This result is in contrast to the facile preparation of the analogous complexes of platinum(II), cfs-[PtCl,(CO)(PRs)] (R = Et, Pr, Bu), from [Pt&l,@'R&] and CO [7] :

The reactions of carbon monoxide with salts of palladium(H) are complex, frequently giving ill-defmed complexes or mixtures of complexes in formal oxidation states 0 to t2 [l, 21. Neutral, mononuclear carbonyl complexes of palladium are both rare and, when known, are normally labile. No welldefmed, neutral carbonyl complex of paUadium(I1) has been described [2]. The use of polymer chains with Lewis base anchor-sites to immobilize metal complexes in discreet and sometimes otherwise unattainable environments is well established [3]. As part of a continuing study of the structures and catalytic activities of such systems [4], we herein report results of an investigation into the interaction of palladium (II) with carbon monoxide and triphenylphosphine or polymers with Ph*P-anchor-sites.

A solution of PdCl#'hCN)2 in benzene was stirred at room temperature under an atmosphere of CO for three days. On reducing the volume of the solution under a stream of CO and subsequent dilution with methylcyclohexane,

[PdCl,(CO)(PhCN)] , (I), was thrown down as an impure brown powder. The material showed infra-red bands at 2295 (m, PhCN), 1990 (VW), 1947 (vs, CO) and 327 @'d-Cl) cm-', which, are consistent with the postulated formula. The material decomposed over 100 'C to yield CO (8.3%, Calc. 9.08%). The CO evolved was sequentially purified by gas chromatography, methanated, and detected and estimated using a flame-ionisation detector. This method has been found to be both rapid and simple for the estimation of CO [5] and was used throughout this study.

Reaction of [PdCl#hCN),] with CO and subsequent treatment with an equimolar amount of triphenylphosphine gave (Eq. 1) the known dinuclear complex [PWW'Ph3)~l, (2) [Cl.